The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Electric heaters generally include a substrate, a dielectric layer disposed on the substrate, a resistive heating layer disposed on the dielectric layer, and a protective layer disposed on the resistive heating layer. The dielectric layer, the resistive heating layer, and the protective layer may be broadly called “functional layers.” One or more of the functional layers of the electric heaters may be in the form of a film by depositing a material onto a surface or a substrate.
On a microscopic scale, a deposited film may have an uneven surface due to existing features or trenches on the substrate surface. A top surface of the deposited film generally undergoes a planarization process in order to flatten the top surface and to provide more uniform performance of the functional layer. However, the planarization process may undesirably remove excessive material from the deposited film, making the thickness of the final deposited film deviate from its designed thickness. Moreover, when the deposited film is a dielectric layer with an electrical element embedded therein, the dielectric integrity of the film may be compromised due to the reduced thickness of the dielectric layer, resulting in poor performance of the electric heater.